This invention relates to an apparatus for etching silicon wafers, particularly vertical junction solar cell wafers.
It is well known in the art to etch silicon with an anisotropic etchant such as an alkali metal hydroxide in aqueous solution. It is also well known to fabricate vertical junction solar cells by employing an anisotropic etchant. U.S. Pat. No. 3,985,579, issued Oct. 12, 1976 to William P. Rahilly, describes a process for fabricating a vertical multijunction solar cell having a plurality of channels providing vertical junctions formed in the upper surface of a semiconductor substrate which includes the steps of:
1. Forming an oxide over an entire P-type silicon slice with (110) orientation.
2. Photolithographically producing open lines in a photoresist applied over the oxide surface. The opened lines are accurately aligned parallel to the (111) planes in the silicon.
3. Removing the oxide in the opened areas.
4. Removing the remaining photoresist.
5. Etching the wafer in an aqueous solution of KOH to a desired channel depth.
It has been observed by the inventor that there exists no apparatus for etching silicon wafers for fabricating vertical junction solar cells.
Accordingly, it is an object of the present invention to provide an apparatus for etching silicon wafers for fabricating vertical junction solar cells.
Other objects and advantages of the present invention will be apparent to those skilled in the art from a consideration of the following detailed disclosure.